Foundries are central to the production of the machinery used in modern society. Virtually every mechanical device contains parts manufactured in a foundry. There are more than 200,000 workers employed in US foundries, and the number is growing rapidly internationally as world wide industrialization proceeds. By the nature of the processes conducted in foundries, the work is hazardous. There are many health and safety hazards in foundries, but foundries are typically small businesses with fewer than 100 employees. Facilities of this size rarely have in-house safety and health capability, so they rely upon generic guidelines when designing and implementing systems of exposure control. This has been the case for ventilation systems which have been applied to control airborne contaminants in foundries. Unacceptable exposures frequently persist even when these guidelines have been implemented. Preliminary research indicates that exposure control systems may be improved by including information on contaminant generation rates and the resulting airborne concentrations, and detailed work activity exposure analysis. The information can be developed using a material balance modeling approach, with work place exposure measurements. The major goal of this research is to develop a material balance model and a detailed exposure analysis as the basis to design, install and evaluate control technology to control pouring line exposures in a cast iron foundry. The specific aims of this study include the development of carbon monoxide emission factors for castings, and the use of these factors in a material balance model developed from research conducted at the National Institute for Occupational Safety and Health. Together with a detailed work activity exposure analysis of the casting process, a control technology system will be designed, and installed in a test foundry. After the performance of the system in reducing exposures has been optimized, a set of design specifications will be prepared and disseminated to other foundries where similar exposure problems exist.